Rendering

\begin{aligned}&E_1 & (1)\\&E_2 & (2)\\&E_3 & (3)\end{aligned}

with release 0.9.0-alpha1 kills the last line of output. 0.8.3 leaves it intact.
Appending \\ to the last line adds it back in.
Sorry for not contributing a dedicated test suite entry, my platform does not support Node.js. Found when testing katex.renderToString with Duktape.
Might have to do with #337.